INDEX 



807 



Hormones, controlling colour changes, 92 

 photoperiodism, in animals, 18 

 in plants, 12 

 plant. See Auxins. 

 See also Pituitary, Sinus gland. 

 Hombill, ocular movements, 696 

 Horse {Equns caballus), 446 

 accommodation, 642, 643 

 angle gamma, 677 

 anterior chamber, 465 

 area centralis, 485 

 blood supply to eye, 500 

 brain, 533 

 cerebral cortex, 543 

 chiasma, 487 

 cilia, 492 



colour vision in, 635 

 conjunctiva, 491 

 cornea, 453 



epithelium of, 452 

 corpora nigra, 469 

 eyes of, 447, 449, 450 

 lacrimal gland, 493 



passages, 494 

 nictitating membrane, 493 

 optic axis, 688 

 orbit, 498 



pectinate ligament, 464 

 Prejvalski's, 686 

 pupils, 471 



reactions of, 472 

 ramp retina, 642, 643 

 refraction of, 639 



retinal vascularization, 478, 480, 481 

 tapetum fibrosum, 457, 458 

 visual acuity, 664 

 field, binocular. 689 

 uniocular, 670, 672 

 See also Equidae. 

 Hovius. circle of, 472 

 Humming birds, visual acuity, 662 



See also Calypte. 

 Humours, four, of Aristotle, 549 

 Hycena, 444, 445 

 optic axis, 688 

 pupils, 470, 471, 612 

 reactions of, 472 

 brunnea, pupils, 470 

 striata, pupils, 470 

 Hysenidse, 445 



Hyaloid vessels, in anurans, 340 

 birds, 415 

 placentals, 476, 477 



Hyaloid vessels, in snakes, 390 



teleosts, 299 

 Hydra, 182 



dermatoptic sensitivity in, 32 



nerve-net, 515 



phototactic reactions of, 571 

 Hydracarina, eyes of, 216 



vision of, 579 

 Hydrochoerus capybara. See Capj'bara. 

 Hydroides, conditioning of, 573 



reactions of, 573 

 Hydrophinse. accommodation in, 641, 649 



pupils, 612, 655 

 Hydrotropism, 33 

 Hydrozoa, 182 



>SVe also Hydra, Obelia, etc. 

 Hygrobates, eyes of, 216 

 Hyla, 334 



area centralis, 344 



fundus, 341 



iris, 337 



movement, perception of, 705 



visual acuity, 661 



arborea, 341 



colour changes in, 86, 105 

 vision in, 628 



ccerulea, eyelids, 345 

 iris, PL III 

 pupil, 339 



vasta, pupil, 339 

 Hylobates. See Gibbon. 

 Hymenolcemus malacorhynchus, binocular 



field, 687 

 Hymenoptera, 219, 220 



neuro-endocrine system, 555 



jS'ee also Apis, Bombus, Vespa, etc. 

 Hynobius, scleral cartilage in, 347 

 Hyperoodon. See Whale, beaked. 

 Hyperpiesine, 561 

 Hypnarce, electric organ of, 751 

 Hypogeophis, eyes of, 730 

 Hypopachus incrassatus, scleral bone in, 



335 

 Hypophysis, 538, 557 

 Hypothalamo -hypophyseal system, 552, 



556 

 Hypothalamus, 539 



hormones and, 550 



reactions of, 541 

 Hypotony and hyperpituitarism, 561 

 Hypsiglena, retina, pure-rod, 610 



visual cells, 391 

 Hypsiprymnus. See Kangaroo, rat-. 



